Using our computer controlled scanning system, PIQUANT, it is planned to pursue the detailed quantitative study of the banding pattern of human chromosomes, both in "normal" and "abnormal" individuals. We propose to establish the exact position of all major bands (with their corresponding variances) and the amplitude of each band (with their variances) for "normal" individuals. This means taking several cultures and cells of each individual. It includes the use of twins to establish the genetic component of the variations encountered. The relationship of the quantitative banding patterns of parents with that of their children will be studied. If highly significant differences between individuals of band position or amplitude can be proven, it will be attempted to establish whether such deviations are related to disease, with a known genetic component. Initial measurements will be done with Giemsa banded metaphases but measurements of bands produced by other procedures, e.g. the C-bands and their relationship to the G-band measurements may prove useful. The computer programs to measure the bands in a cytogenetically and mathematically meaningful way and to analyze the results in a statistically valid manner will be written as part of this work. The successful programs and procedures may be adapted for use with the computer microscope which has been installed, as an alternative to the use of negatives.